#..
    This file contains code that supports manipulating and using collections like lists
    and dictionaries.

use "lib/metaprogramming.nom"
use "lib/control_flow.nom"
use "lib/operators.nom"

# List/dict functions:

# Indexing
compile [..]
    %index st to last in %list, %index nd to last in %list, %index rd to last in %list
    %index th to last in %list
..to "utils.nth_to_last(\(%list as lua), \(%index as lua))"

parse [first in %list, first %list] as: 1 st in %list
parse [last in %list, last %list] as: 1 st to last in %list

# Membership testing
action [%item is in %list, %list contains %item, %list has %item]
    for %key = %value in %list
        if (%key is %item): return (yes)
    return (no)

action [..]
    %item isn't in %list, %item is not in %list
    %list doesn't contain %item, %list does not contain %item
    %list doesn't have %item, %list does not have %item
..
    for %key = %value in %list
        if (%key is %item): return (no)
    return (yes)

compile [%list has key %index, %list has index %index] to ".."
    ((\(%list as lua))[\(%index as lua)] ~= nil)

compile [..]
    %list doesn't have key %index, %list does not have key %index
    %list doesn't have index %index, %list does not have index %index
..to "((\(%list as lua))[\(%index as lua)] ~= nil)"

compile [length of %list, size of %list, size %list, number of %list, len %list] to
    "utils.size(\(%list as lua))"

compile [append %item to %list, add %item to %list] to
    "table.insert(\(%list as lua), \(%item as lua))"

compile [pop from %list, remove last from %list] to
    "table.remove(\(%list as lua))"

compile [remove index %index from %list] to
    "table.remove(\(%list as lua), \(%index as lua))"


action [flatten %lists]
    %flat <- []
    for %list in %lists
        for %item in %list
            add %item to %flat
    return %flat

action [entries in %dict]
    [{key:%k, value:%v} for %k=%v in %dict]

action [keys in %dict]
    [%k for %k=%v in %dict]

action [values in %dict]
    [%v for %k=%v in %dict]

# List Comprehension
immediately
    compile [%expression for %item in %iterable] to
        assume ((%item's "type") is "Var") or barf ".."
            List comprehension has the wrong type for the loop variable. Expected Var, but got: \(%item's "type")
        return ".."
            (function()
                local comprehension = {};
                for i,\(%item as lua) in ipairs(\(%iterable as lua)) do
                    comprehension[i] = \(%expression as lua);
                end
                return comprehension;
            end)()
    parse [%expression for all %iterable] as: %expression for % in %iterable

    compile [%expression for %key = %value in %iterable] to
        assume ((%key's "type") is "Var") or barf ".."
            List comprehension has the wrong type for the key loop variable. Expected Var, but got: \(%key's "type")
        assume ((%value's "type") is "Var") or barf ".."
            List comprehension has the wrong type for the value loop variable. Expected Var, but got: \(%value's "type")
        return ".."
            (function()
                local comprehension = {};
                for \(%key as lua), \(%value as lua) in pairs(\(%iterable as lua)) do
                    comprehension[i] = \(%expression as lua)
                end
                return comprehension;
            end)()

# Dict comprehensions
immediately
    compile [%key = %value for %item in %iterable] to
        assume ((%item's "type") is "Var") or barf ".."
            Dict comprehension has the wrong type for the loop variable. Expected Var, but got: \(%item's "type")
        return ".."
            (function()
                local comprehension = {};
                for i,\(%item as lua) in ipairs(\(%iterable as lua)) do
                    comprehension[\(%key as lua)] = \(%value as lua)
                end
                return comprehension;
            end)()
    parse [%key = %value for all %iterable] as: %key = %value for % in %iterable

    compile [%key = %value for %src_key = %src_value in %iterable] to
        assume ((%src_key's "type") is "Var") or barf ".."
            Dict comprehension has the wrong type for the key loop variable. Expected Var, but got: \(%src_key's "type")
        assume ((%src_value's "type") is "Var") or barf ".."
            Dict comprehension has the wrong type for the value loop variable. Expected Var, but got: \(%src_value's "type")
        return ".."
            (function()
                local comprehension = {};
                for \(%src_key as lua), \(%src_value as lua) in pairs(\(%iterable as lua)) do
                    comprehension[\(%key as lua)] = \(%value as lua);
                end
                return comprehension;
            end)()

# Sorting:
compile [sort %items] to "table.sort(\(%items as lua))"
compile [sort %items by %key_expr] to ".."
    utils.sort(\(%items as lua), function(\(\% as lua))
        return \(%key_expr as lua);
    end)

action [%items sorted]
    %copy <- (% for all %items)
    sort %copy
    return %copy
action [%items sorted by %key]
    %copy <- (% for all %items)
    sort %copy by %key
    return %copy

action [unique %items]
    [%k for %k=%v in (%=(yes) for all %items)]

# Metatable stuff
compile [set %dict's metatable to %metatable] to code ".."
    setmetatable(\(%dict as lua), \(%metatable as lua));

compile [new counter] to "setmetatable({}, {__index=function() return 0; end})"

compile [new default dict] to ".."
    setmetatable({}, {__index=function(self, key)
        t = {};
        self[key] = t;
        return t;
    end})"

# TODO: maybe make a generator/coroutine?